refactor(backend): optimize database safety, validator performance, and scheduler concurrency

- Fix SQL injection risks in proxy_repo and task_repo
- Atomic acquire_pending with UPDATE ... RETURNING
- Reuse aiohttp ClientSession in ValidatorService
- Replace polling with asyncio.Event in SchedulerService
- Optimize ValidationQueue.drain with asyncio.Condition
- Concurrent plugin crawling with asyncio.gather
- Unify ProxyRaw model import path
- Fix test baseline and remove tracked __pycache__ files

app/services/scheduler_service.py

@@ -20,12 +20,14 @@ class SchedulerService:
         self.proxy_repo = proxy_repo
         self.interval_minutes = 30
         self.running = False
+        self._stop_event = asyncio.Event()
         self._task: asyncio.Task | None = None
 
     async def start(self):
         if self.running:
             logger.warning("Scheduler already running")
             return
+        self._stop_event.clear()
         self.running = True
         await self.validation_queue.start()
         self._task = asyncio.create_task(self._run_loop())
@@ -33,6 +35,7 @@ class SchedulerService:
 
     async def stop(self):
         self.running = False
+        self._stop_event.set()
         if self._task:
             self._task.cancel()
             try:
@@ -55,10 +58,10 @@ class SchedulerService:
             except Exception as e:
                 logger.error(f"Scheduler loop error: {e}")
             # 等待下一次
-            for _ in range(self.interval_minutes * 60):
-                if not self.running:
-                    break
-                await asyncio.sleep(1)
+            try:
+                await asyncio.wait_for(self._stop_event.wait(), timeout=self.interval_minutes * 60)
+            except asyncio.TimeoutError:
+                pass
 
     async def _do_validate_all(self):
         """验证数据库中所有存量代理"""